High alpha and high intrinsic viscosity pulp production apparatuses, methods and systems

ABSTRACT

The HIGH ALPHA AND HIGH INTRINSIC VISCOSITY PULP PRODUCTION APPARATUSES, METHODS AND SYSTEMS (hereinafter “HIGH-A HIGH-IV PULP PRODUCTION”) disclosed herein provide for pulp processing used in connection with Kraft Processes (KP) or Pre Hydrolysis Kraft Processes (PHKP), embodiments employing a Cold Caustic Extraction (CCE) stage and/or appropriate washing and bleaching stages, resulting in pulp with high Intrinsic Viscosity (IV) and high purity, such as may be as determined by alpha cellulose content, and adequate brightness for use downstream in applications such as high tensile regenerated cellulose and ether applications, or other applications employing high IV pulp with significant purity (e.g., alpha cellulose&gt;92%).

This application for letters patent disclosure document describesinventive aspects that include various novel innovations (hereinafter“disclosure”) and contains material that is subject to copyright, maskwork, and/or other intellectual property protection. The respectiveowners of such intellectual property have no objection to the facsimilereproduction of the disclosure by anyone as it appears in publishedPatent Office file/records, but otherwise reserve all rights.

FIELD

The present innovations generally address pulp processing, and moreparticularly, include HIGH ALPHA AND HIGH INTRINSIC VISCOSITY PULPPRODUCTION APPARATUSES, METHODS AND SYSTEMS.

BACKGROUND

The use of pre-hydrolysis kraft process (“PHKP”) associated to coldcaustic extraction (“CCE”) has been described previously, such as U.S.Pat. Nos. 8,734,612 and 8,535,480. Both patents are hereby incorporatedby reference as if set forth fully herein. A schematic description ofsuch a method is given as a block diagram in FIG. 1.

The association of cooking process and CCE process has been describedand presents useful industrial application for production of high puritypulps (alpha cellulose content from 96% to 98%). One aspect of the artis the management of CCE filtrate as an alkali source, avoiding or atleast minimizing the precipitation of hemicelluloses, and has beensuccessfully used in industrial installation.

Resulting pulp is washed, bleached and dried in appropriate manner toresult in commercial product especially suitable to manufacture ofcellulose acetate (tri-acetate and di-acetate).

Such process produces Elemental Chlorine Free (ECF) bleached pulp withtypical IV of 700 mg/l at high brightness level (above 92% ISO) that canbe extended up to 800 mg/l at normal market pulp brightness (89% to 90%ISO).

Cooking process may be conducted in batch or continuous installations.State of art installations are batch with most of current production ofhigh purity pulp.

Batch cooking plants implement PHKP in a very effective way, producinghigh quality product through long times (year or more) without necessityto stop for cleaning or convert to KP production.

Continuous cooking PHKP has been historically tried in single vesselinstallations producing pulp of acceptable quality, but with foulingproblems leading to short campaign times and the need to run KPcampaigns or stop the unit for cleaning (typically measure in a fewweeks' time).

Recently PHKP has been re-introduced in continuous cooking by means of a2 vessel system separating the PH phase from KP phase. This system seemsto have a better performance but still suffers from some foulingproblems.

In such system most of the purification work is done in the PHKP cooking121, with a typical removal of more than 80% of the hemicellulosepresent in the wood. Typically such cooking process will deliver pulpwith alpha cellulose content in the range of 94-96%.

Pulp from cooking will typically have Kappa Number (“KN”) in the range 7to 13 and IV in the range 700-1100 depending on raw material and cookingconditions (P factor (PF) typically >200, H factor (HF) typically <500,alkali charge typically 18-24% Effective Alkali as NaOH on oven dry (OD)wood basis).

After cooking, pulp is washed and cleaned to remove debris 122, uncookedmaterial and other rejects, following to the CCE stage 123.

The subsequent CCE stage will boost purity level up to 98% in alphacellulose by application of alkali charge in the range of 300-600 kgNaOH/kg OD pulp and temperatures up to 50° C.

As mentioned before CCE acts by solubilizing the low molecular weightsubstances present in the pulp fiber. With such action not onlyhemicellulose and degraded cellulose molecules are removed from thefibers, but also some degraded lignin is removed, resulting in a KN dropof up to 3 units.

After CCE stage, pulp is washed 124 to remove residual caustic contentand also lignin, hemicellulose and low degree of polymerization (“dp”)cellulose in CCE process. The filtrate from this process is referred toas CCE filtrate or CCE liquor, and is recycled to cooking process.Excess filtrate can be exported for other areas (e.g., evaporationplant, hemicellulose recovery plant, lignin recovery plant, other pulpproduction line, etc.).

In bleaching plant 125 pulp residual lignin is chemically removed andbrightness is increased in a multi stage setup with typically 2 to 5stages. The bleached pulp may then be subjected to further screeningand/or sand removal 126; dewatering, pressing and/or drying 128; andfinishing in rolls or bales 128 to result in commercial productespecially suitable to manufacture of cellulose acetate (tri-acetate anddi-acetate).

An ECF process may include Chlorine Dioxide (D) stage, AlkalineExtraction (E) stage, Oxygen (O2) stage and Peroxide (P) stage.

D-P being an instance of 2 stage sequence and D-E-D-E-D being aninstance of 5-stage sequence, where E may or may not be reinforced by O2or Peroxide. Other chemicals like Per Acetic Acid (PAA) or enzymes maybe used.

Total Chlorine Free (TCF) bleaching will be typically 2 or 3 stages withO2, Ozone (O3) and P stages. PAA and enzymes may be also used.

TCF bleaching in general is less selective leading to lower bleachedpulp viscosity.

Pulp bleaching is not a perfectly selective process and cellulose IVwill be typically reduced by at least 100 mg/l, and more typically200-300 mg/l, resulting in lower final product viscosity, lower overallprocess yield (conversion of wood to final goods) and sometimes lowerpulp purity (as alpha-cellulose) due to cellulose degradation.

SUMMARY

The HIGH ALPHA AND HIGH INTRINSIC VISCOSITY PULP PRODUCTION APPARATUSES,METHODS AND SYSTEMS (hereinafter “High-A High-IV Pulp Production”)disclosed herein in various embodiments provide for pulp processing usedin connection with Kraft Processes (“KP”) and Pre Hydrolysis KraftProcesses (“PHKP”), embodiments employing a Cold Caustic Extraction(“CCE”) stage and/or appropriate washing and bleaching stages, resultingin pulp with high Intrinsic Viscosity (“IV”) and high purity, such asmay be as determined by alpha cellulose content, and adequate brightnessfor use downstream in applications such as high tensile regeneratedcellulose and ether applications, or other applications employing highIV pulp with significant purity (e.g., alpha cellulose>92%).

In one embodiment, an improved method is disclosed for generating highIV pulp with good purity and brightness levels by means of the combinedused of cooking and CCE process, where filtrate from CCE stage may beused in cooking process without any previous purification treatment. Asuitable bleaching process of high selectivity is indicated as a meansto maximize final product IV.

In one aspect, the method includes the use of non-purified CCE filtratein the cooking step, while the aforementioned art states thatpurification by membrane separation like Nano or Ultra filtration isrequired.

The performance of a CCE filtrate purification process is eliminated, insome embodiments, by the use of White Liquor Pad.

In another aspect, the current application produces high IntrinsicViscosity pulp, suitable for cellulose ether and high tensileregenerated cellulose, while in aforementioned art conditions areoptimized to produce pulp suitable for Lyocell or Viscose application,that are low Intrinsic Viscosity products for textile market.

In KP and PHKP, H-factor is described as a control parameter combiningreaction temperature and reaction time from cooking stage so as to reacha desired lignin content in the end of said stage. Lignin content may beindirectly determined, e.g., by KN (described in Tappi T-236) or similartest methods form other standards (e.g., as ISO, ASTM, NBR, JIS, and/orthe like).

Likewise in PHKP, P-factor is described as a control parameter combiningreaction temperature and reaction time from pre-hydrolysis stage, inorder to reach desired pulp purity as an end result of the whole cookingprocess. Pulp purity may be indirectly determined, e.g., by alphacellulose test (Tappi T-203) or alkali solubility methods (Tappi T-235)or similar from other standards.

The dp of cellulose can be indirectly evaluated, e.g., by means ofIntrinsic Viscosity test method (ISO 5351) or similar from otherstandards, were IV bears a direct correlation with cellulose dp. High IVvalues indicate high cellulose dp, and conversely low IV indicates lowcellulose dp, typically resulting from extensive cellulose degradation.

More accurate dp measurements can be performed, e.g., by gel permeationchromatography of dissolved cellulose polymer, but that method may notbe practical in some instances for process control, so IV or otherequivalent viscosity measurement may alternatively be adopted.

Embodiments of the CCE stage use a low temperature high alkalinityenvironment to induce extensive pulp swelling, leading to diffusion oflow molecular weight material such as hemicelluloses, degraded celluloseand degraded lignin, increasing the alpha cellulose content of theresulting pulp.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying appendices and/or drawings illustrate variousnon-limiting, example, innovative aspects in accordance with the presentdescriptions:

FIG. 1 presents an example of prior art process flow for pulpproduction.

FIG. 2 shows an example process flow diagram in one embodiment of High-AHigh-IV Pulp Production.

FIGS. 3A-3B show a cooking recipe, including logical flow and detailedprocess parameters, of the cooking process in one embodiment of High-AHigh-IV Pulp Production.

FIG. 4 shows an example representation of a single vessel continuousdigester with steam phase pre-hydrolysis in one embodiment of High-AHigh-IV Pulp Production.

FIG. 5 shows an example representation of a single vessel continuousdigester with aqueous phase prehydrolysis in one embodiment of High-AHigh-IV Pulp Production.

FIG. 6 shows an example representation of a two vessel continuousdigester, with the pre-hydrolysis (aqueous and/or steam phase) beingperformed in the first vessel and the following cooking steps in thesecond vessel, in one embodiment of High-A High-IV Pulp Production.

FIG. 7 shows a representation of a batch cooking plant process in oneembodiment of High-A High-IV Pulp Production.

DETAILED DESCRIPTION

The HIGH ALPHA AND HIGH INTRINSIC VISCOSITY PULP PRODUCTION APPARATUSES,METHODS AND SYSTEMS (hereinafter “High-A High-IV Pulp Production”)disclosed herein in various embodiments address optimization of processconditions from the combined cooking and CCE stages resulting in high IVbleached pulp (e.g., >1200 ml/g, alpha cellulose content >94% and pulpbrightness >89% ISO). The optimized conditions go beyond the originaldescribed conditions in previous art, but do not require changes in mainequipment.

Embodiments of High-A High-IV Pulp Production may also be applied tocontinuous cooking processes, bringing potential process benefitsregarding process simplification and reduced equipment scalingpotential.

Embodiments of High-A High-IV Pulp Production may include theredistribution of purification work done in cooking and CCE stages,shifting most of the purification effect to the CCE stage (e.g., 55% ormore of hemicellulose reduction; in some implementations, 90% or more),while reducing the cooking process hemicellulose reduction effect.

This change in purification strategy, combined with describedmodifications in cooking process and adequate, i.e., selective bleachingconditions results in high viscosity pulp with dissolving grade purityand brightness, suitable for specialty applications such as celluloseethers and high strength regenerated cellulose.

CCE filtrate can be partially or completely recycled to the cookingplant without any treatment as applied in previous art U.S. Pat. No.8,734,612, which is incorporated in its entirety herein by reference.

Pulp produced from cooking will typically have viscosity above 1200 ml/gat a bleachable KN (below 20 for hardwood pulp) and purity above 85% inalpha cellulose.

In the subsequent CCE stage, pulp purity is increased up to 96% alphacellulose content. For some applications in which mercerized cellulosecontent is irrelevant, alpha cellulose purity may be increased up to98%.

KN will drop significantly (typically 4-5 units) and once most of low dpcellulose and hemicellulose products are removed a significant increasein average pulp dp is seen, bringing IV above about 1300 ml/g level.

In some implementations, a subsequent high selectivity bleachingsequence with 2 or 3 stages (D-P or D-EP-D) will bring brightness to acommercial level (e.g., 88%-91% ISO; in some implementations 89%-90%ISO) at final IV level above 1200 ml/g.

See comparison of previous art results with current results on table 1.

TABLE 1 Results of pilot scale experiments demonstrating the current artpulp quality compared with prior art pulp quality (U.S. Pat. No.8,734,612). Raw material used was Eucalyptus Urograndis. Pulp producedat same brightness and purity level that can be reached in previous artwith 30% higher Intrinsic Viscosity. Prior Art Pulp Quality Parameter(U.S. Pat. No. 8,734,612) Current Intrinsic Viscosity (g/ml) 950 1270Brightness (% ISO) 90.0 90.7 S18 (%) 3.8 3.2 S10 (%) 4.7 4.0 Calculatedalpha cellulose (%) 95.8 96.4

Such viscosity and purity levels are not currently available fromHardwood KP or PHKP, being only obtained by Sulphite cooking of Softwoodor by the use of cotton linter.

The CCE filtrate will have high hemicellulose content and alsosignificant lignin content, being a potential candidate forhemicellulose and lignin recovery process. Independently of suchrecovery processes, the CCE Filtrate can be recycled to the cookingplant without other treatment than temperature and alkalinityadjustments as the main alkali source for the cooking process (e.g.,more than 70% of total EA charge applied on BD wood).

Examples of process conditions to achieve the desired viscosity andpurity levels are described in the following exemplary statements.

In implementations, the raw material can be hardwood, softwood ornon-wood source.

Cooking method may be PHKP, with KP being considered as a particularcase of PHKP were P factor is 0 (Zero).

Cooking equipment may be batch cook or continuous.

FIG. 2 shows an example of logic flow for high-A high-IV pulp productionin one embodiment from raw material to finished product.

FIGS. 3A-3B present detailed cooking process parameters, i.e., thecooking recipe, for high-A high-IV pulp production in one embodiment. Inone embodiment, actual conditions in one or more steps may slightlydeviate from the ones presented due to implementation particularities(e.g. batch or continuous digester, or different strainer setarrangement on continuous digesters) or due to other accessory processeslimitations (e.g. steam supply or evaporation plant). Detailedprocedures of each step in the cooking recipe are disclosed further.Some steps may have alternative procedures disclosed, but notrepresented in the recipe flowsheet for simplification.

In some implementations, a PHKP cooking process 221 may include woodchips being fed into the digester 301 and heated 302 to, e.g., 110-135°C. (e.g., in one implementation to 115-125° C.) with, e.g., direct steaminjection or similar method and kept at such temperature for time enough303 to reach a P factor from 0 to 100 (e.g., in one implementation, from10 to 30). In this condition air removal is at acceptable levels and amild pre hydrolysis will take place (no pre hydrolysis for theparticular case of 0 P factor).

In one implementation, the acid aqueous phase containing hemicellulose,cellulose and lignin degradation products, referred as hydrolysate, maybe extracted or displaced from the digester. This stream can be recycledto the chip feeding and/or chip heating step as a form of heating orchip transport media. In one implementation, the hydrolysate can bepurified and its key valuable molecules, such as acetic acid, furfuraland sugar monomers and oligomers, separated as an additional revenuestream, or can be neutralized with any alkaline stream and sent to theevaporation plant.

A next step, in one implementation, includes the addition of a whiteliquor pad 314, e.g., to avoid hemicellulose and lignin precipitation.In one implementation, the white liquor pad amount will correspond to0-5% of the BD wood weight.

A next step, in one implementation, includes the addition of a highvolume of CCE filtrate 324 for wood chip alkali impregnation, e.g.,corresponding from 70 to 100% of total alkali requirement for cooking.

This filtrate may have a typical concentration of, e.g., 20 to 80 gEffective Alkali (EA)/l, with EA expressed as NaOH (e.g., in oneimplementation, 40-60 g EA/l). This filtrate may have its concentrationincreased by addition of white liquor.

In some implementations, CCE filtrate will be pre heated to, e.g.,90-140° C. (e.g., in one implementation, to 120-130° C.).

Sufficient impregnation time can be achieved, by leaving the digesterstatic or circulating the liquor through the digester in the case ofbatch digesters, or having a sufficient retention time at theimpregnation zone in continuous digesters.

A next step, in some implementations, includes heating of chips to reachthe desired cooking temperature, e.g., in the range of 130-160° C.(e.g., in one implementation to 140-150° C.). Heating can be provided,for example, by the addition of hot black liquor that will displace thespent CCE filtrate and/or by forced circulation of the digester liquorto an external heat exchanger, or another form of external heating.

With implementations including the addition of hot black liquor 305,concentration of, e.g., 5-45 g EA/l (e.g., in one implementation 10-20 gEA/l) may be employed in some implementations and can be adjusted byaddition of fresh white liquor or CCE filtrate. Black liquor temperaturemay be, e.g., 130-170° C. (e.g., in one implementation, 150-160° C.).The addition of hot black liquor may be sufficient to reach the cookingtemperature target, or a few degrees (e.g., not more than 10° C.) lower.If the latter, in one implementation, the liquor inside the digester canbe circulated to an external form of heating to reach its desiredtemperature.

Once target temperature is reached it may be kept 306 until a desiredH-factor is reached. An H-Factor target may be set, in oneimplementation, to result in bleachable pulp of suitable KN (e.g., forhardwood KN may be from 15-20 (e.g., in one implementation, from16-18)).

An extra alkali charge (0-5%), either in the form of CCE filtrate orpure white liquor, may be added at one or multiple intermediateH-factors, e.g., to avoid the residual alkali concentration inside thedigester reaching a low level that will promote lignin and hemicelluloseprecipitation trough the cooking phase.

A next step, in one implementation, includes the cooking liquordisplacement with cold wash liquor 307, containing some residual alkali,e.g., higher than 2 gEA/l, such as to avoid lignin and hemicelluloseprecipitation.

In some implementations, the wash liquor may have its alkalinityincreased, e.g., by the use of white liquor or CCE filtrate. Wash liquortemperature may be adjusted to a level such that the pulp discharge fromthe cooking vessel will be below boiling conditions.

A next step, in one implementation, includes pulp discharge from thecooking vessel 308, e.g., to an atmospheric discharge tank, atmosphericwashing equipment (e.g. atmospheric diffuser), pressurized washingequipment (e.g. pressure diffuser), and/or the like.

A next step, in one implementation, includes washing of the pulp. In oneimplementation, the pulp may also be screened 222. Screening may beperformed before or after washing of pulp, or after CCE stage.

A next step, in one implementation, includes the addition of cold freshalkali 223, e.g., in the form of NaOH or White Liquor or a combinationof both to perform the Cold Caustic Extraction (CCE) process.

For example, white liquor with a concentration from, e.g., 100-130 gEA/l (e.g., in one implementation from 115-125 gEA/l) and sulfidity of,e.g., 18-40% (e.g., in one implementation from 28-32%) may be used afterbeing cooled, so as to adjust CCE stage to operate at temperature from,e.g., 20-50° C. (e.g., in one implementation from 30-35° C.) at a pulpmass consistency of, e.g., 3 to 15% in fiber weight (e.g., in oneimplementation from 8-12%) and an alkali concentration in the pulpslurry of, e.g., 50-120 g EA/l (e.g., in one implementation from 60-80 gEA/l). Pulp slurry concentration may be adjusted by the addition of adilution liquid, e.g., in one implementation, filtrate from a washingstage after the CCE.

Retention time in CCE stages can, in various implementations, be from afew minutes to several hours. For example, in one implementation, thetime span may be in the range of 15 to 30 minutes.

A next step, in one implementation, includes counter current washing ofCCE pulp 224, e.g., in 2 or more washing stages (e.g., in oneimplementation from 3 to 4 stages), such as to recover CCE filtrate andminimize alkali and organic dissolved solid loss to subsequent bleachingprocesses.

Washing can be done with any kind of washing equipment (e.g., press,wash press, pressurized filters, vacuum filters, pressurized andatmospheric diffusers, and/or the like).

Various washing media may be used, e.g., pure water, condensate fromevaporation plant, and/or other suitable washing liquor (e.g., EOPfiltrate, P filtrate, and/or the like). Washing media temperature maydepend, for example, on washing machine specifics, overall process mass,heat balance, and/or the like, and may be in the range of 50-85° C., butnot restricted to that range.

A next step, in one implementation, includes bleaching the pulp 225,e.g., in a high selective bleaching sequence in order to minimizeviscosity loss.

For Hardwood pulp, a 3-stage ECF sequence may be employed to reach finalbrightness of 89-91% ISO, whereas a 2-stage ECF sequence may be used forbrightness level 86-90% ISO.

The bleaching sequence may include the use of viscosity preservers suchas magnesium salts, chelating agents, and/or the like for the control oftransition metals.

Next steps, in some implementations, may further include additionalscreening and/or sand removal 226; dewatering, pressing and drying 227;and finishing the resulting pulp in rolls, bales, and/or the like 228.

EXAMPLES

Further embodiments of High-A High-IV Pulp Production are demonstratedin the following examples. In some instances, the examples are based onprinciples presented in FIG. 2 and as well as the recipes presented inFIGS. 3A and 3B. Deviation and particulars are described in eachexample.

Example 1

Kraft process for high Intrinsic Viscosity high Purity pulp in oneembodiment, 3 using a single vessel steam phase continuous digesterwhere main alkali source is untreated CCE filtrate.

In this case the sequence shown in FIG. 2 is implemented in a singlevessel continuous digester as described, in one embodiment, in FIG. 4.The cooking recipe follows closely the one presented in FIGS. 3A-3B.

The downstream process comprises washing, screening, CCE treatment, CCEwashing and ECF bleaching as previously described.

Wood Chips (401) are processed via chip feeding system and transferred(402) to Digester vessel. In various implementations, the chip feedingsystem may comprise, e.g., chip silo with chip pumping system to feedthe digester, chip silo with High Pressure Feeder to feed the digester,direct digester feeding with a metering and pressure locking device,and/or the like.

First Digester Section

In digester top the chips may be heated up with Steam (403) to desiredtemperature and retention time to achieve a given P factor. Chip leveland/or liquor level may be controlled to establish defined specifiedretention time. Digester Pressure may be controlled to achieve thedesired temperature without boiling.

Second Digester Section

A set of strainers may be located in a second digester section, such asto establish a circulation loop. Liquor may be extracted from digester,receive white liquor charge (407) and returned to digester via centralpipe (404) above the said set of strainers. This circulation flow may beemployed to facilitate white liquor pad effect.

Third Digester Section

A second set of strainers may be located in a third digester section,such as to establish a circulation loop. Liquor may be extracted fromdigester (419), receive a CCE filtrate charge (408) and returned todigester via central pipe (405) above the said set of strainers. Thiscirculation flow may be employed to facilitate CCE filtrate distributionand impregnation process. Retention time may be selected to facilitateimpregnation.

In one implementation, this circulation loop may include extractioncapability (414) to facilitate digester liquor level control.

Fourth Digester Section

A third set of strainers may be located in a fourth digester section toestablish a circulation loop. Liquor may be extracted from digester,receive a CCE filtrate charge (410) and/or white liquor charge (409),may be heated up with steam (411) and returned to digester via centralpipe (406) above the said set of strainers. This circulation flow may beemployed to facilitate alkali distribution and heat up process.Retention time may be selected to facilitate cooking time to desired Hfactor.

In one implementation, residual alkali may be adjusted in this step tofacilitate kappa number control.

In one implementation, this circulation loop may include extractioncapability (412) to facilitate digester liquor level control.

Fifth Digester Section

A fourth set of strainers may be located in a fifth digester section,such as to establish the main digester extraction flow. The extractionpipes (418) may be directed to heat recovery system, liquor filtration,and/or the like and then sent to evaporation plant.

Sixth Digester Section

Cold wash filtrate (416) may be introduced to digester bottom, such asto allow washing and/or cooling before the pulp discharge (417).

Retention time in this section may be selected to facilitate pulpcooling and to provide a washing effect as well.

In one implementation, white liquor (415) and/or CCE filtrate (413) maybe used to correct the wash filtrate alkalinity.

In one implementation, pulp may be discharged from digester (417) at aselected temperature, below boiling point, to the subsequent processstep (e.g., blow tank, pressure diffuser, and/or the like).

Example 2

Kraft process for high Intrinsic Viscosity high Purity pulp in oneembodiment using a single vessel hydraulic phase continuous digesterwere main alkali source is untreated CCE filtrate.

Principle diagram shown in one embodiment in FIG. 5.

Similar to principles described in connection with example 1 above,except that digester is hydraulically filled, employing one additionalset of strainers in First digester section in order to establish acirculation loop. Liquor may be extracted from digester, heated andreturned to digester via central pipe above the said set of strainers(520). This circulation flow may be employed to facilitate heat up todesired temperature. An extraction line may be employed to facilitatedigester pressure control (512, 514, 521).

After the modified First digester section, the process may resumethrough remaining sections as described in example 1.

Example 3

Kraft process for high Intrinsic Viscosity high Purity pulp in oneembodiment, using a two vessel steam phase continuous digester were mainalkali source is untreated CCE filtrate.

Principle diagram shown in one embodiment in FIG. 6.

Similar to principles described in connection with example 1 above,except that a second vessel for pre hydrolysis may be introduced betweenchip feeding system and Digester. In some implementations, such vesselcan be steam/liquor phase, hydraulically pressurized, and/or the like.

In one implementation, chips may be heated up to specified prehydrolysis temperature, such as by direct steam injection in case ofsteam/liquor phase vessel 622, or by means of indirect heating by theestablishment of a liquor circulating loop (strainer, circulation pumpand heat exchanger) in the top of said vessel.

In one implementation, chip transfer for digester 620 may be achieved bypressurization with steam and/or compressed air in the top of suchsteam/liquor phase vessel and/or by use of a pressurization pump in chipfeeding system, such as in the case of a hydraulically filled vessel.

In another implementation, chip pumping may be used for chiptransference between pre hydrolysis vessel and digester.

Such vessel may employ a retention time set so as to reach a desired Pfactor.

After transfer to digester, the process may proceed as described inexample 1, with the possible optimization of doing the white liquor padaddition in the transfer loop between both said vessels (pre hydrolysisand digester, 620 and 621) using this circulation loop as a replacementii from sections 1 and 2.

Example 4

Kraft process for high Intrinsic Viscosity high Purity pulp in oneembodiment using a batch digester system where main alkali source isuntreated CCE filtrate.

Principle diagram shown in one embodiment in FIG. 7.

In one implementation, a first step the cooking vessel (digester)includes filling with wood chips 701. In one implementation, a smallamount of steam may be added to facilitate chip packing and start theheating process.

In one implementation, a second step may include, with the cookingvessel full of chips and closed, heating up to specified temperature andpressure 702.

In one implementation, a third step may include maintaining specifiedconditions 2 (e.g., of temperature and pressure) until target P factoris reached 703.

In one implementation, a fourth step may include introducing whiteliquor pad to the cooking vessel 704.

In one implementation, a fifth step may include introducing a specifiedamount of pre heated CCE filtrate in the cooking vessel and waiting fora specified degree of impregnation to be achieved 705.

In one implementation, a sixth step may include heating up the vessel tocooking temperature 706. For example, that may be achieved bycirculating the liquor present in the vessel through an external heater,by displacing the liquor present in the vessel with hot black liquor ofcontrolled alkalinity, and/or the like. In one implementation, in thisstage extra alkali charge from fresh white liquor or from CCE filtratecan be introduced, such as via circulation, displacement, and/or thelike.

In one implementation, a seventh step may include keeping specifiedconditions until target H factor is reached 707.

In one implementation, an eighth step may include displacing the liquorpresent in the vessel 708, e.g., with cooled wash liquor so as to cooldown the product to below boiling point at discharge condition.

In one implementation, a ninth step may include discharging the cookingvessel 709, e.g., so it is empty and ready to restart the cooking cycle.

In order to address various issues and advance the art, the entirety ofthis application for HIGH ALPHA AND HIGH INTRINSIC VISCOSITY PULPPRODUCTION APPARATUSES, METHODS AND SYSTEMS (including the Cover Page,Title, Headings, Field, Background, Summary, Brief Description of theDrawings, Detailed Description, Claims, Abstract, Figures, Appendices,and otherwise) shows, by way of illustration, various embodiments inwhich the claimed innovations may be practiced. The advantages andfeatures of the application are of a representative sample ofembodiments only, and are not exhaustive and/or exclusive. They arepresented only to assist in understanding and teach the claimedprinciples. It should be understood that they are not representative ofall claimed innovations. As such, certain aspects of the disclosure havenot been discussed herein. That alternate embodiments may not have beenpresented for a specific portion of the innovations or that furtherundescribed alternate embodiments may be available for a portion is notto be considered a disclaimer of those alternate embodiments. It will beappreciated that many of those undescribed embodiments incorporate thesame principles of the innovations and others are equivalent. Thus, itis to be understood that other embodiments may be utilized andfunctional, logical, operational, organizational, structural and/ortopological modifications may be made without departing from the scopeand/or spirit of the disclosure. As such, all examples and/orembodiments are deemed to be non-limiting throughout this disclosure.Also, no inference should be drawn regarding those embodiments discussedherein relative to those not discussed herein other than it is as suchfor purposes of reducing space and repetition. For instance, it is to beunderstood that the logical and/or topological structure of anycombination of any process steps and/or feature sets as described in thefigures and/or throughout are not limited to a fixed operating orderand/or arrangement, but rather, any disclosed order is exemplary and allequivalents, regardless of order, are contemplated by the disclosure. Assuch, some of these features may be mutually contradictory, in that theycannot be simultaneously present in a single embodiment. Similarly, somefeatures are applicable to one aspect of the innovations, andinapplicable to others. In addition, the disclosure includes otherinnovations not presently claimed. Applicant reserves all rights inthose presently unclaimed innovations including the right to claim suchinnovations, file additional applications, continuations, continuationsin part, divisionals, and/or the like thereof. As such, it should beunderstood that advantages, embodiments, examples, functional, features,logical, operational, organizational, structural, topological, and/orother aspects of the disclosure are not to be considered limitations onthe disclosure as defined by the claims or limitations on equivalents tothe claims.

What is claimed is:
 1. A method for high intrinsic viscosity pulpproduction, comprising: pre-hydrolyzing raw material in a digester viasteam heating to obtain a pre-hydrolysis condition comprising a P factorfrom 0 to 100; adding a white liquor pad to the pre-hydrolyzed rawmaterial; adding non-purified cold caustic extraction filtrate toproduce alkali impregnated pre-hydrolyzed raw material; heating thealkali impregnated pre-hydrolyzed raw material to reach a targettemperature and holding for a cooking time to reach a target H-factorand produce pulp; displacing cooking liquor with a cold wash liquoruntil the pulp is below boiling conditions; discharging the pulp fromthe digester; washing the pulp; screening the pulp; adding cold freshalkali to the pulp for cold caustic extraction; performing countercurrent washing of the pulp to recover the cold caustic extractionfiltrate; and bleaching the pulp in a high selective bleaching sequence.2. The method of claim 1, wherein the raw material comprises hardwood.3. The method of claim 2, wherein the target H-factor is selected toyield a kappa number in the range from 15 to
 20. 4. The method of claim3, wherein the kappa number is in the range from 16 to
 18. 5. The methodof claim 1, wherein the raw material comprises softwood.
 6. The methodof claim 1, wherein the raw material comprises a non-wood sourcematerial.
 7. The method of claim 1, wherein cooking process comprisesPHKP cooking.
 8. The method of claim 7, wherein the PHKP cookingcomprises KP cooking.
 9. The method of claim 1, wherein the white liquorpad comprises 0% to 5% of the raw material weight.
 10. The method ofclaim 1, further comprising: pre-heating the non-purified cold causticextraction filtrate to a filtrate temperature in the range of 90° C. to140° C.
 11. The method of claim 10, wherein the filtrate temperature isin the range of 120° C. to 130° C.
 12. The method of claim 1, whereinthe non-purified cold caustic extraction filtrate has a filtrateconcentration in the range of 20 gEA/l to 80 gEA/l.
 13. The method ofclaim 12, wherein the filtrate concentration is in the range of 40 gEA/lto 60 gEA/l.
 14. The method of claim 1, wherein heating the alkaliimpregnated raw material reaches the target temperature in the range of130° C. to 160° C.
 15. The method of claim 14, wherein the targettemperature is in the range of 140° C. to 150° C.
 16. The method ofclaim 1, wherein heating the alkali impregnated raw material furthercomprises: adding a quantity of hot black liquor heated to a liquortemperature in the range of 130° C. to 170° C.
 17. The method of claim1, further comprising: adding extra alkali charge to the raw materialduring cooking at intermediate H-factor values before the targetH-factor is reached.
 18. The method of claim 1, wherein the cold washliquor comprises residual alkali having a concentration higher than 2gEA/l.
 19. The method of claim 1, wherein the pulp is discharged fromthe digester to at least one of an atmospheric discharge tank,atmospheric washing equipment, and pressurized washing equipment. 20.The method of claim 1, wherein the cold fresh alkali is NaOH, whiteliquor, or a combination of both.
 21. The method of claim 1, wherein thecold fresh alkali is the white liquor having a white liquorconcentration in the range of 100 gEA/l to 130 gEA/l and a sulfidity inthe range of 18% to 40%.
 22. The method of claim 1, wherein the coldfresh alkali is added for the cold caustic extraction to operate at aCCE temperature in the range from 20° C. to 50° C.,
 23. The method ofclaim 1, wherein the cold caustic extraction is performed for anextraction time in the range from 15 to 30 minutes.
 24. The method ofclaim 1, wherein the counter current washing is performed by at leastone of a press, wash press, pressurized filter, vacuum filter,pressurized diffuser, and atmospheric diffuser.
 25. The method of claim1, wherein the counter current washing is performed with wash mediacomprising at least one of pure water and evaporation plant concentrate.26. The method of claim 1, wherein the raw material is a hardwood, andwherein the high selective bleaching sequence comprises a three stageECF sequence to reach a final brightness of between 89% and 91% ISO. 27.The method of claim 1, wherein bleaching the pulp in a high selectivebleaching sequence further comprises: adding at least one viscositypreserver.
 28. The method of claim 27, wherein the at least oneviscosity preserver comprises at least one of a magnesium salt and achelating agent.
 29. The method of claim 1, further comprising:dewatering the pulp; pressing the pulp; drying the pulp; and forming thepulp into rolls or bales.
 30. The method of claim 1, wherein thedigester comprises a batch digester.
 31. The method of claim 1, whereinthe digester comprises a continuous digester.
 32. A method for highintrinsic viscosity pulp production, comprising: performingpre-hydrolysis kraft process cooking of hardwood chips in a digester viasteam heating to obtain a pre-hydrolysis condition comprising a P factorfrom 10 to 30; adding a white liquor pad to the cooked hardwood chips,wherein the white liquor pad comprises 0% to 5% of a weight of thehardwood chips; pre-heating a non-purified cold caustic extractionfiltrate having a filtrate concentration of between 40 gEA/l and 60 gEA/l to a filtrate temperature of between 120° C. and 130° C.; addingthe non-purified cold caustic extraction filtrate to produce alkaliimpregnated cooked hardwood chips; heating the alkali impregnated cookedhardwood chips to a target temperature between 140° C. and 150° C. toreach a target H-factor corresponding to a kappa number between 16 and18 and produce pulp; displacing cooking liquor with a cold wash liquorcomprising residual alkali at concentration higher than 2 gEA/l untilthe pulp is below boiling conditions; discharging the pulp from thedigester to at least one of an atmospheric discharge tank, atmosphericwashing equipment; and pressurized washing equipment; washing the pulp;screening the pulp; adding cold fresh alkali, comprising NaOH, whiteliquor, or both, to the pulp for cold caustic extraction to operate atan extraction temperature of between 30° C. and 35° C. for an extractiontime of between 15 and 30 minutes; performing counter current washing ofthe pulp at a washing temperature of between 50° C. and 85° C. torecover the cold caustic extraction filtrate; bleaching the pulp in ahigh selective bleaching sequence comprising a three stage ECF sequenceto reach final brightness of between 89% and 91% ISO, wherein thebleaching includes adding at least one of a magnesium salt and achelating agent; dewatering the pulp; pressing the pulp; drying thepulp; and forming the pulp into rolls or bales.
 33. A system for highintrinsic viscosity pulp production, comprising: a chip feeder forproviding raw material; a digester for receiving raw material from thechip feeder, the digester comprising: a pre-hydrolysis stage forsteam-heating the raw material to obtain a pre-hydrolysis conditioncomprising a P factor from 0 to 100, a white liquor pad stage for addinga white liquor pad to the raw material, an impregnation stage for addingnon-purified cold caustic extraction filtrate to produce alkaliimpregnated raw material, a heating stage to heat the alkali impregnatedraw material to reach a target cooking temperature, a cooking stage toreach a target H-factor and produce pulp, and a washing or displacementstage to reduce pulp temperature; pulp screening equipment to removeshives and knots; pulp washers for removing dissolved solids; a coldcaustic extraction stage, comprising: mixing equipment for adding a coldalkali source to the pulp, a reactor to perform desired retention time,and a washing stage for counter-current washing of the pulp to recovercold caustic extraction filtrate; a bleaching plant for bleaching thepulp in a high selective bleaching sequence; and a pulp dryer machineand finishing line to produce pulp bales or rolls.